i) Technical Field of the Invention
This invention relates to an action of a piano which can be switched between a normal performance mode and a silent performance mode.
ii) Description of the Related Art
A piano has been known that has an electronic sound source and an acoustic sound mechanism so that it can be played in an electronic sound mode as well as in an acoustic sound mode. For example, such a piano comprises switching means for abutting and separating an action, which transmits the key depression to a hammer, onto and away from a key. Generation of a string striking sound can be prohibited by preventing the key depression from being transmitted to the hammer when the piano is in the electronic sound mode (silent performance mode). Therefore, if a player plays this piano in the silent performance mode and listens to the sounds produced by an electronic sound source through headphones, etc., the sounds do not escape to the outside and the player can freely enjoy playing without disturbing the neighborhood, even in a housing complex or an area with houses lined closely together.
Unexamined Japanese Patent Publication No. 10-20858 discloses a keyboard instrument such that when the player depresses the key in the silent performance mode, not only is the action prevented from being abut upon the key, but a dummy load is also applied to the key so as to give a touch and feel for the fingers of the player similar to that obtainable in the normal performance mode.
In this case, the action arranged between the key and the string for swinging the hammer is separated away from the key by means of a wippen lifter, and a reset spring is made to abut resiliently upon the upper face of the key in order to apply the dummy load. When the player depresses the key against the urging force of this reset spring and then releases the key, the key is moved back to its original position due to the spring force of the reset spring. In the silent performance mode, the touch and feel based upon the action mechanism is replaced with the touch and feel based on the reset spring.
According to the aforementioned keyboard instrument, however, the spring force of the reset spring, which is made to abut resiliently on the upper face of the key, is applied to the key in the silent performance mode. Since the spring force is varied depending on the amount of displacement of the key due to the key depression of the player, the touch and feel from the normal performance mode cannot be reproduced with great precision.
It is also feared that the spring may be eventually worn and damaged. The spring force may be gradually lost due to repeated expansion and contraction of the spring caused by the key depression.